A cloak of invisibility is truly a powerful magic item for mischief. The wearer of this cloak is constantly under the effect of an invisibility spell- that is, they are invisible.

That is not to say they can do anything- since its the lesser version of this spell, they cannot take any offensive actions and expect to remain hidden. Still, as long as the wearer does not move or can move quietly, they can 'obtain' a lot of things that would normally be beyond their reach.